Merrimack watershed bacteria results: June 28, 2022

Dear river and watershed friends,

After a pandemic hiatus, the Upper Merrimack Monitoring Program Adopt-a-River Site Sponsors and volunteers began the 2022 bacteria sampling season with 100% sampling at 100% of its eleven sites from Franklin to Bow.

The results shown below are the probable number of E. coli bacteria colonies for every 100 millilitres of water. All warm blooded animals (including we humans) have E. coli in their guts. That means that bacteria are an indicator that poop has found its way to the water. This could be a result of stormwater runoff, failed septic systems, mis-connected pipes that are meant to transport household waste to a treatment plant, pet or wildlife waste from river watershed and, and other sources.

To protect public health, State designated swim beaches are not allowed to exceed 88 colonies of E. coli per 100ml. Class B waters (all of our sites are designated as Class B) shall not exceed 406 colonies. These designations do not always reflect real-time water quality. The designation indicates what uses, e.g., swimming, fishing, should be supported by maintaining water quality.

Almost all of the sites this week are below the swim beach designation. Site 1 is well below the Class B designation. These low bacteria counts are expected when there has been little or no rain.

You hear us say often, “When it rains, it’s poor,” which means that you may wish to wait a day or so after it rains before recreating in a surface water. Sample results are as of Tuesday morning, June 28, 2022. Results may change from day-to-day, depending on upstream conditions and rainstorms that may have occurred after Tuesday morning.